1. Field of the Invention
The present invention relates to a functional cosmetic material. More particularly, it relates to a functional cosmetic material obtained from a lactic acid fermentation broth, which exhibits an active oxygen species-scavenging, a DNA repair system-reinforcing and an immune system-reinforcing properties.
2. Description of the Prior Art
Recent research on the cell biology leads to a development of functional cosmetics for, for example, retarding aging in humans. One aspect of the development of functional cosmetics is to provide cosmetics which have an ability of scavenging harmful active oxygen species. The active oxygen species are byproducts generated from the oxygen metabolism in humans and other mammals, and include, for example, superoxide radical (O.sub.2 --), hydroxyl radical(.OH) and singlet oxygen (.sup.1 O.sub.2). These active oxygen species have critical roles in lipid superoxidation, protein denaturation and nucleic acid mutation. Although the harmful active oxygen species are continually destroyed by protective enzymes, for example, superoxide dismutase, catalase and glutathione peroxidase, such defenses are not 100% efficient, and particularly aging and environmental stimuli make the defenses by the protective enzymes less efficient. Thus chemical destruction of cells can result, an example of the cell damage caused by the oxygen species is damage to DNA, which virtually may resulted in a formation of cancer (Leibvitz B. E. & Siegel B. W. 1980, J. Gerontol. 35:45). Active oxygen species also are related to inflammation (William F. P. et al., Proc. Natl. Acad. Sci. USA 77:1159 (1980)) and to various diseases (Chikako Nishigen M. D. et al., J. Invest. Derma. 1989).
The raising needs for an artificial active agent which can scavenge the harmful oxygen species lead to a development of cosmetic materials containing superoxide dismutase, flavonoids and lactoferins. However, these active components have a drawback, when used in cosmetic compositions for the skin, that the superoxide dismutase is sparingly soluble in oils and unstable as well as is poor in its adsorption and absorption to the skin. Further, lactoferins have a drawback that their production from milk by extraction methods is complicate and the yield is low.
Another aspect of the development of functional cosmetics is to find out an agent which can reinforce the DNA repair systems in the skin. DNA is a cell's genetic material which carries genetic information and plays most important roles in PG,4 the survival of cells. DNA molecules are always exposed to various sources causing a damage thereto and also have specific enzymatic mechanisms to repair damaged sites. However, continued environmental stresses and aging make the DNA repair by the enzymatic machinery less efficient. The damaged cells, which are not repaired, may become cancerous and cause abnormally high skin cell death and skin diseases (V. A. Bohr et al., 1989, Laboratory Investigation 61(2):143). Particularly, excess exposure to UV light of sunlight leads to a formation of thymine dimer which causes cell death and DNA mutation.
So far some cosmetic materials are developed as an anti-mutation agent in order to impart DNA repair ability to cosmetic compositions and such cosmetic materials include, for example, specific plant extracts, placenta extracts and Actinomycetes strain extracts. However, the extracts derived from plants and Actinomycetes strains have a weak substantivity to the skin and may induce adverse effects. Placenta extracts have no such problems, but their production is limited.
Another aspect of the development of the functional cosmetic compositions is to provide an agent which can reinforce the immune systems of the skin. The immune system is a defence machinery of a living body, which maintains and protects the living body from the environment containing a large variety of infectious microbial agents. Aging considerably weaken the capacity of the immune system, resulting in various skin diseases (Atsushi Uchida, Fragrance J., 19C9):29 (1991). However, so far no satisfactory agent for enhancing the function of the dermal immune systems, which can be used in cosmetic compositions, is proposed.
By the way, it has been known that an useful moisturizing factor can be obtained from skim milk. Particularly, U.S. Pat. No. 4,524,136 discloses a process for preparing a cosmetic material comprising the steps of simultaneously carring out in skim milk the processes of lactic acid fermentation by lactic acid bacteria and decomposition of casein by proteases; and simultaneously carrying out the processes of sterilization of lactic acid bacteria and inactivation of proteases to produce a cosmetic material. However, the said patent is based on a fact that lactates is an useful moisturizing factor and its purpose is to provide a transparent cosmetic material which can be easily absorbed and adsorbed to the skin, and therefore, has no relation to the present invention.
The present inventors had found out that there may be obtained a cosmetic material, which is useful to scavenge harmful oxygen species and has moisturizing property, by fermenting a lactic acid bacteria in skim milk or powdered skim milk cantaining metal ions and proteases and treating the harvested cells (Korean Patent Application No. 90-6419). However, the cosmetic material obtained by the method described in said patent application is insufficient in its ability of reinforcing the DNA repair system. Moreover, the method is less economical of cost and of DNA repair-reinforcing efficacy of the product because it uses only supernatant obtained from centrifugation of the broken cells.
Therefore, there remains a need for a cosmetic material which shows a harmful active oxygen species-scavenging, a DNA repair system-reinforcing and an immune system-reinforcing properties as well as shows good compatiability with and absorption to the skin, and less irritate the skin.